The invention relates to the use of additives in the preparation of crop protection composition spray mixtures, in particular as additives for tank mixtures of specific tetramic acid pesticides according to formula (I).
The tetramic acid pesticides referred to herein are the pesticides of formula (I)
wherein                X, Y and Z independently of each other are C1-4alkyl, C3-6cycloalkyl, C1-4haloalkyl, C1-4alkoxy, halogen, phenyl or phenyl substituted by C1-4alkyl, C1-4haloalkyl, halogen or cyano;        m and n, independently of each other, are 0, 1, 2 or 3 and m+n is 0, 1, 2 or 3;        G is hydrogen, a metal, ammonium, sulfonium or a latentiating group;        R is hydrogen, C1-6alkyl, C1-6haloalkyl, C1-6cyanoalkyl, benzyl, C1-4alkoxy(C1-4)alkyl, C1-4alkoxy(C1-4)alkoxy(C1-4)alkyl or a group selected from G; and        A is hydrogen, C1-6alkyl, C1-6haloalkyl, C3-6cycloalkyl, C3-6cycloalkyl(C1-4)alkyl, or C3-6cycloalkyl(C1-4)alkyl where in the cycloalkyl moiety a methylene group is replaced by O, S or NR0, where R0 is C1-6alkyl or C1-6alkoxy, or A is C2-6alkenyl, C2-6haloalkenyl, C3-6alkynyl, C1-6cyanoalkyl, benzyl, C1-4alkoxy(C1-4)alkyl, C1-4alkoxy(C1-4)alkoxy(C1-4)alkyl, oxetanyl, tetrahydrofuranyl, tetrahydropyranyl, C1-6alkylcarbonyl, C1-6alkoxycarbonyl, C3-6cycloalkylcarbonyl, N-di(C1-6alkyl)carbamoyl, benzoyl, C1-6alkylsulfonyl, phenylsulfonyl, C1-4alkylthio(C1-4)alkyl, C1-4alkylsulfinyl(C1-4)alkyl or C1-4alkylsulfonyl(C1-4)alkyl;        Or A is O-A1 where A1 is selected from one of A, as defined above, or furanyl -(C1-4)alkyl, tetrahydro-thiofuranyl, tetrahydro-thiopyranyl or 1-(C1-4)alkoxy-piperidin-4-yl or an agrochemically acceptable salt or an N-oxide thereof.        
The compounds of formula (I) above have insecticidal properties. These compounds have a systemic mode of action. They penetrate the leaf cuticle and enter the plant's vascular system, moving both upwards and downwards via phloem and xylem to new shoot, leaf and root tissues. This “2-way systemicity” results in effective control of hidden pests on above- and below-ground plant parts and on new growth. Insects ingest the active ingredient by feeding on the plant. The efficacy of the compounds according to formula (I) i.e. increased uptake can be enhanced when formulating the active ingredient into a composition suitable for application on crops.
One type of formulation often used for agrochemical active ingredients are suspension concentrates. Suspension concentrate formulations are stable suspensions of solid pesticide(s) in a fluid usually intended for dilution before use. Ideally, the suspension should be stable (i.e. not settle out). Suspension concentrate formulations are generally diluted with water prior to customary spraying via nozzles. Other common types of formulations include soluble powders (SP), water soluble granules (SG), water dispersible granules (WG), wettable powders (WP), emulsifiable concentrates (EC), and dispersible concentrates (DC), emulsion in water (EW), oil dispersion (OD), or soluble liquid (SL). Besides the active substance(s) (or also called active ingredient(s)), also other auxiliaries, such as Surfactants, emulsifiers, dispersants, wetting agents, antifreezes, antifoams, biocides, solvents, stabilizer, anti-microbials, pigments, buffers, surface-active substances etc. can be present in the formulation; such substances are known to the person skilled in the art of formulation.
In crop protection, additives, also called adjuvants or penetrants, are usually used to improve the efficacy of crop protection composition active ingredients. The adjuvants are capable of penetrating the wax layer on the leaves of the plant thereby allowing systemic active ingredients increased access to the epidermal cells of the plant.
These are either added to the aqueous spray mixture shortly before spraying separately to the crop protection composition (as tank mixture adjuvants) or incorporated directly into the crop protection composition concentrate together with other auxiliaries (a built-in formulation).
Tank mixture adjuvants are added to the water in the same tank separately from the formulated active ingredient and are distributed within the entire spray mixture by stirring.
The tank mixture adjuvants can be added to water before or after the formulated active ingredient.
Many different types of tank mixture adjuvants are known to the person skilled in the art of agrochemical formulations e.g. mineral oils, vegetable oils, trans-esterified vegetables oils, polysiloxanes, non-ionic organic surfactants, ionic surfactants, buffering (or acidifying) agents, or polymers such as Nufilm 17, which is an emusifiable film forming polymer based on natural Pinolene or other polymers, based on Terpenes.
However, the formulation of tetramic acid compounds according to formula (I), involves more challenges than just the simple improvement of its efficacy with adjuvants. An overdose of tetramic acid compounds (ACCase chemistry) could lead to phytotoxic reactions in sensitive plant species. It is well known that different acetyl-CoA carboxylase isoforms exist across higher plants. The completely different structure of ACCase isoforms in Gramineae and dicotyledonous plants could for example explain different sensitivities towards tetramic acid compounds (e.g. ACCase herbicides) (see Konishi et al. (1996) Plant Cell Physiol. 37,117-122 and Schulte et al. (1997) Proc. Natl. Acad. Sci. U.S.A. 94, 3456-3470). But also across dicotyledonous crops different sensitivities across plant families (e.g. Brassicacea; see Price et al. (2003) Biochem. J. 375, 415-423) could exist.
However, usually when applying known tank-mix additives (also referred to herein as tank mixture adjuvants or tank-mix adjuvants) to reduce phytotoxicity, the efficacy of the tetramic acid compound is usually compromised. When applying tank-mix additives known to increase efficacy, it is known that phytoxicity is usually positively correlated i.e. the higher the efficacy, the higher the phytoxicity risk and vice versa. The lower the efficacy, the lower the phytoxic risk.
Thus, the technical problem to be solved is finding a suitable tank-mix adjuvant that will reduce any potential phytoxicity of the tetramic acid according to formula (I) to an acceptable level, whilst simultaneously at least maintaining, if not maximising, the efficacy of the tetramic acid according to formula (I).
The solution to this problem was not obvious, since most adjuvants that increase efficacy, would generally also cause an increase in the compounds' inherent phytoxicity. Furthermore, the tank-mix of the compounds of formula (I) and the selected tank-mixture adjuvants must ensure that the tetramic acid compounds according to formula (I) are predominantly in their keto-enol form when sprayed on the field.
It has been found that surprisingly polysiloxanes adjuvants are very suitable as tank-mix adjuvants for the tetramic acid compounds according to the invention. Surprisingly, these polysiloxane adjuvants solve the two main problems of the tetramic acids mentioned above i.e. acceptable phytotoxicity and maximum efficacy. Other adjuvants known to the skilled person have failed to solve the two problems adequatly.
The use of these spreading polysiloxane surfactants, such as, for example, BREAK-THRU® S-240 or BREAK-THRU® S-233, from Evonik GmbH, in combination with a pesticide used as an improvement in the pesticide uptake by the plant and generally to an increase in its effectiveness or its efficacy is known. U.S. Pat. No. 6,734,141 describes that especially a low surface tension and not necessarily the spreading is responsible for this increase in efficacy. However, there has never been an indication that compositions such as Break-Thru enable the reduction of phytoxicity of tetramic acid compounds according to formula (I).
The non-expert will maybe assume that all commercial wetting agents or tensides (e.g. in cosmetic uses or as component of household cleaning compositions) will promote the efficacy of pesticides. This is wrong and has been shown in several publications e.g. in Pesticide Formulation and Adjuvant Technology, edited by Chester L. Foy and David W. Pritchard. CRC Press LLC, 1996, pp. 323-349).
It is therefore still surprising and not apparent that the substances of the present invention can reduce the phytotoxicity of the tetramic acid pesticides according to formula (I) whilst maintaining and even improving the efficacy of the active ingredients. Within the context of the invention, numerous adjuvants were tested; of these, surprisingly, specifically only polysiloxanes proved to be suitable.
Two other surprisingly good adjuvants for this chemistry class were Geropon® DOS-PG and Trend® 90. Unexpectedly these also reduced the phytotoxicity, whilst providing increased the efficacy of the tetramic acid compounds of formula (I).